Abstract: The effects of 10 components in the culture solution on the accumulation of polypeptides after 5 days of soybean germination by means of infiltration were investigated. Using Plackett-Burman experiment design, GA3, CaCl2, aluminium chloride (AlCl3) and manganous sulfate (MnSO4) were identified as main factors that significantly positively affect polypeptide accumulation. The quadratic polynomial regression model for polypeptide content in germinated soybean versus the four variables established based on Box-Behnken experiment design was statistically significant (P＜0.05) and could allow the prediction of polypeptide accumulation. The optimal concentrations of GA3, CaCl2, AlCl3 and MnSO4 in the culture solution were 61.00 μmol/L, and 11.20, 10.13, 12.17 mmol/L, respectively. The polypeptide content in germinated soybean cultured under these conditions was 162.57 mg/g, which was 2.10-fold and 3.97-fold higher than the control and non-germinated soybean, respectively. Therefore, the optimized culture solution can significantly increase polypeptide content in germinated soybean.

Key words: germinated soybean, ploypeptide, accumulation, culture solution composition, response surface methodology